A piezo-based rotational inertia shaker for the active control of rotating machinery

This paper presents an axisymmetric rotational inertia shaker for reducing the structure borne noise radiated by rotating machinery. This modular inertia shaker uses a piezostack to generate a compensating force on a rotating element by accelerating a ring shaped mass. The piezostack is controlled using an adaptive shunt circuit, which emulates the impedance of a variable inductance. The inertia shaker is tested on an experimental test bed where a disturbance force excites a rotating shaft, which is mounted in a frame. As a result, noise is radiated by a plate that is attached to the frame. The performance of the inertia shaker is first evaluated during non-rotating tests. When the virtual inductance is tuned optimally, a shaft vibration reduction of more than 12 dB and a corresponding noise reduction of 9 dB are obtained. Afterwards, the performance has also been checked during a rotating test. A comparable reduction as in the non-rotating tests is obtained when the piezostack is in the same direction as the disturbance force, while there is nearly no reduction when the piezostack is in the perpendicular direction to the disturbance.